There are many references disclosed in the prior art regarding the illuminated keyboard for desktop computers, laptop or notebook computers, or network TVs to make the keyboard visible in a low light or dark environment and to facilitate keyboard strike operation, such as U.S. Pat. Nos. 6,284,988, 6,322,229, 6,199,996, 6,554,442, and 6,179,432, and R.O.C. patent publication Nos. 509955, 465777, 535385, 438035, 570235, 468833, and 516671. They mostly include an embedded luminous sheet to emit light to enable users to recognize the striking position of the keyboard.
They also have a common feature, i.e. the luminous element and the keycap are spaced only by an elastic member and an actuating mechanism. And most of them have the keycap, elastic member and actuating mechanism made from permeable material (some have the keycap made from impermeable material, but the character symbol on the keycap is made from the permeable material) so that when the entire luminous sheet emits light, the keyboard has an even backlight. Such type of illumination creates problems for users when in use. This is because the illuminated keyboard usually is used in a low light environment such as in an airplane, car and the like where the ambient light is weak. The evenly lighted keyboard makes the luminosity of the entire body too strong and affects the surrounding people. Moreover, the visibility of the keyboard is generally low in such an environment, with the entire plate evenly lighted, it is more difficult to recognize the symbol on each keycap. Even if the symbol is made from the impermeable material, or the keycap is made from the impermeable material and the symbol is made from permeable material, light emitting from the neighboring keycaps will create light interference and make recognition difficult. For users who are not familiar with the keycap symbols, striking errors often occur and wrong instructions are made frequently.